In recent years, there is a growing need for shampoos having conditioning effects such as smoothness of foam during foaming, smoothness of the hair during rinsing and a frictionless touch, as well as basic performances such as detergency, a good foaming property and an abundance of foam. A variety of amino-modified silicones are added to satisfy such a need. For example, a modified silicone having an average molecular weight from about 3000 to 100000 which is listed in the CTFA under the name of amodimethicone is incorporated in a shampoo. Shampoos containing such an amino-modified silicone are however unsatisfactory in its foaming property and its amount of foam volume and in addition, the smoothness provided by this silicone still remains unsatisfactory.
With a view to improving the smoothness property, a hair cosmetic composition containing an amino-modified silicone derivative in which a side chain bonded to a silicon atom has a group containing both a hydroxy group and a nitrogen atom is under investigation. For example, WO 2003/066007 pertains to a hair cosmetic composition containing an amino-modified silicone. Particularly in Example 1 of this document is described a shampoo composition using, as an anionic surfactant, sodium lauryl ether sulfate whose average number of moles of ethylene oxide addition is 2. The shampoo composition containing an amino-modified silicone derivative has however problems such as deterioration in the foaming property and a reduction in foam volume.
Alkyl sulfates typical as a component of a cleansing composition have been used most frequently because of their high detergency and power of producing an abundance of foam. When alkyl sulfates are used singly as an anionic component of a cleansing composition, however, hair feel imparted by shampooing is not satisfactory, because friction is caused between individual hairs. In order to improve the hair feel during shampooing, polyoxyethylene-added alkyl sulfates (alkyl ether sulfates), of which those having 2 to 3 moles, on average, of ethylene oxide have been employed because of good hair feel during shampooing. Although addition of ethylene oxide overcomes the problem of friction between individual hairs, it deteriorates the foaming speed greatly. Any one of the above-described methods is unsatisfactory for attaining quick foaming, good feel of the foam and the reduction in friction between hairs.
Alkyl ether sulfates added with 2 moles, on average, of ethylene oxide, which are typically and conventionally used an alkyl ether sulfates, are composed of about 20 wt. % of a 0 mole adduct, from 10 to less than 20 wt. % of 1, 2, and 3 mole adducts respectively, and the balance of 4 or greater mole adducts. The foaming property is therefore improved by adjusting the number of moles of ethylene oxide addition. For example, in JP-A-11-507079, described is an aqueous shampoo composition having a high conditioning effect, which contains from 5 to 50 wt. % of a surfactant component containing alkyl ether sulfates added with 1 to 8 moles of ethylene oxide and an amphoteric surfactant, and containing less than 5 wt. % of alkyl ether sulfates added with not greater than 1 mole of ethylene oxide. This shampoo composition is however unsatisfactory in both its foaming property and foam quality.